The lungs are the primary organs of respiration, which consists of ventilation and gas exchange in the lungs and oxygen transport to the cells of the body. Cedars-Sinai Hospital notes that on average, a normally active person breathes almost 20,000 liters of air.
Location
The lungs are located in the chest or thoracic cavity on either side of the heart. They begin at about the second thoracic vertebra and extend down to about the second lumbar vertebra. The rib cage wraps around the lungs to help protect them and other organs in the chest. The sternum or breastbone and the vertebral column make up the anterior and posterior regions of the chest and upper back, also helping to protect the lungs.
Conducting Passageways
The conducting division of the lungs consists of all the passageways through which air flows into lung tissue. These passageways are held open by muscle, bone or cartilage. In the lungs, the airways are the trachea, bronchi and bronchioles. The trachea begins below the larynx, or voice box, and is divided into two parts, which enter each lobe of the lungs. The bronchi begin where the trachea enter the lungs and branch into the bronchioles.
Lung Lobes
The lungs are divided into a right and left lobe. The right lobe is superficially divided into three segments and the slightly larger left lobe is divided into two. The lobes consist of the bronchi and bronchioles and the clusters of alveoli at the end of each alveoli. The alveoli are air sacs with extremely thin walls that are surrounded by dense networks of very small blood vessels called capillaries. This allows gas exchange to occur in which the blood receives the oxygen that is breathed in and gives the lungs carbon dioxide from the body to breathe out, as explained by Cedars-Sinai Hospital.
Ventilation
The Canadian Lung Association explains that ventilation is the mechanical movement of air in and out of lungs during inhalation and exhalation. The chest muscles and diaphragm--a large dome-shaped muscle beneath the lungs--help the lungs expand and contract for ventilation.
Gas Exchange
Gas exchange is the second part of respiration. Air entering the lungs has a greater concentration of oxygen than the blood. The National Lung Health Education Program notes that this difference allows oxygen from the inhaled air to diffuse into the blood and carbon dioxide from the lungs to enter the lungs to be breathed out. Gas exchange occurs in the thin-walled alveoli sacs.
